Pumping Device

ABSTRACT

A pumping device includes a frame body, a pump body, a piston rod, a drive shaft, a main guiding member, a carrier block, a plug unit, and a rotary-to-linear motion conversion mechanism disposed between the carrier block and the drive shaft so as to convert rotation of the drive shaft to linear motion of the carrier block. A shaft axis of the drive shaft and a piston axis of the piston rod cooperatively define a vertical plane. A bottom surface of the carrier block is guided by the main guiding member and defines a bottom plane which is orthogonal to the vertical plane.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Taiwanese application No. 102140285, filed on Nov. 6, 2013, the disclosure of which is hereby incorporated in its entirety by reference.

FIELD OF THE INVENTION

This invention relates to a pumping device, more particularly to a pumping device with a rotary-to-linear motion conversion mechanism.

BACKGROUND OF THE INVENTION

As shown in FIG. 1, a conventional pumping device for high performance liquid chromatography (HPLC) includes a base 11, a pump body 12, a piston rod 13, and a driving unit 14. The base 11 extends in a longitudinal direction (X) to terminate at front and rear ends 111, 112. The pump body 12 is mounted to the front end 111 of the base 11 and has an elongated duct 121, an inlet port 122, and an outlet port 123. The piston rod 13 extends along a piston axis and into the elongated duct 121 for reciprocating linear motion therein so as to allow a liquid sample to be drawn into the elongated duct 121 through the inlet port 122, and to drive the liquid sample to be discharged through the outlet port 123. The driving unit 14 is mounted to the base 11, and includes a guiding member 141, a sliding block 142, a screw shaft 143, and a motor 144. The guiding shaft 141 has two ends respectively mounted to the front and rear ends 111, 112. The sliding block 142 has a left segment 1421 which is slidably mounted on the guiding shaft 141, a right segment 1422 to which one end of the piston rod 13 is fixed, and a middle segment 1423 therebetween. The screw shaft 143 extends along a shaft axis and through the middle segment 1423 of the sliding block 142, and can be driven by the motor 144 to rotate about the shaft axis. Rotation of the screw shaft 143 results in a forward motion or a rearward motion of the sliding block 142 on the guiding shaft 141, thereby permitting the reciprocating linear motion of the piston rod 13.

In this conventional pumping device, the piston axis of the piston rod 13 is offset from the shaft axis of the screw shaft 143 in a horizontal direction (Z) so as to permit the piston rod 13 to extend beyond the front end 111 on which the screw shaft 143 is journalled. However, when the rotational torque force of the screw shaft 143 is transferred to the sliding block 142 so as to move the piston rod 13 along the longitudinal direction (X), such mechanical conversion of rotary-to-linear motion will unavoidably impart on the sliding block 142 a wavering motion, which will lead to uneven movement of the piston rod 13 during its reciprocating linear motion. Thus, the piston rod 13 might be prone to breaking after a period of use.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a new pumping device in which a piston rod thereof is less likely to break.

Accordingly, a pumping device of the present invention includes a frame body, a pump body, a piston rod, a drive shaft, a main guiding member, a carrier block, a plug unit, and a rotary-to-linear motion conversion mechanism. The frame body extends in a longitudinal direction and has front and rear ends, and a main chamber defined between the front and rear ends. The front end has a passage extending therethrough and along a passage axis. The pump body defines an elongated duct extending along a pump axis, and is disposed forwardly of the front end such that the elongated duct is aligned with the passage with the pump axis in line with the passage axis. The pump body has an outlet port disposed downstream of the elongated duct, and an inlet port which is in fluid communication with the elongated duct, and which is disposed upstream of the outlet port. The piston rod is disposed in the elongated duct for reciprocating linear motion therein, and extends along a piston axis toward the outlet port to terminate at a head end, and through the passage into the main chamber to terminate at a fixed end. The drive shaft is configured to be journaled in the front and rear ends so as to be rotatable about a shaft axis which is parallel to the piston axis and which is opposite to the piston axis in a transverse direction relative to the longitudinal direction. The shaft axis and the piston axis cooperatively define a vertical plane therebetween. The main guiding member is disposed under the drive shaft, and defines a guideway extending in the longitudinal direction. The carrier block has a bottom surface, a top surface, a forward surface, a rearward surface, a cavity, and a through bore. The bottom surface is configured to be guided by the guideway, and defines a bottom plane orthogonal to the vertical plane. The top surface is opposite to the bottom surface in the transverse direction. The forward surface faces toward the front end. The rearward surface is opposite to the forward surface in the longitudinal direction. The cavity extends through the forward and rearward surfaces along a cavity axis, and includes smaller-dimension front subcavity, a larger-dimension rear subcavity, and a shoulder abutting surface therebetween. The through bore is configured to permit the drive shaft to pass through the forward and rearward surfaces. The plug unit has a grip hole which is configured to permit the fixed end to be fitted therein. The plug unit is configured to be plugged in the smaller-dimension front subcavity such that the fixed end is retained in the grip hole to thereby permit the piston rod to be moved with the carrier block. The rotary-to-linear motion conversion mechanism is disposed between the drive shaft and the carrier block so as to convert rotation of the drive shaft to linear motion of the carrier block to thereby permit the carrier block to move along the guideway when the drive shaft is driven to rotate.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the embodiments of the invention, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view showing a conventional pumping device;

FIG. 2 is a partially exploded view of a pumping device according a first embodiment of the present invention;

FIG. 3 is a perspective view of the first embodiment in an assembled state;

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4; and

FIG. 6 is a cross-sectional view of a pumping device according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before the present invention is described in greater detail, it should be noted herein that same reference numerals are used to denote like elements throughout the specification.

FIGS. 2 to 5 show a pumping device according to a first embodiment of the present invention. The pumping device is adapted for delivering a nano-volume or a micro-volume of liquid, and includes a frame body 2, a pump body 3, a piston rod 4, a plug unit 43, a main guiding member 50, at least one carrier block 52, a drive shaft 53, and a rotary-to-linear motion conversion mechanism 6.

The frame body 2 extends in a longitudinal direction (X) and has front and rear ends 21, 24, and a main chamber 20 defined therebetween. The front end 21 has a passage 211 extending therethrough and along a passage axis (P).

In this embodiment, the frame body 2 has a bottom wall 23 and a top wall 25 opposite to the bottom wall 23 in a transverse direction (Y) relative to the longitudinal direction (X). The bottom wall 23 extends in the longitudinal direction (X) and is disposed between the front and rear ends 21, 24.

The pump body 3 defines an elongated duct 30 extending along a pump axis (P), and is disposed forwardly of the front end 21 such that the elongated duct 30 is aligned with the passage 211 with the passage axis (P) in line with the pump axis (P). The pump body 3 has at least one outlet port 32 disposed downstream of the elongated duct 30, and at least one inlet port 33 which is in fluid communication with the elongated duct 30, and which is disposed upstream of the outlet port 32.

The piston rod 4 is disposed in the elongated duct 30 for reciprocating linear motion therein, and extends along a piston axis (P) toward the outlet port 32 to terminate at a head end 41 and through the passage 211 into the main chamber 20 to terminate at a fixed end 42. The piston rod 4 is disposed above the drive shaft 53.

During a rearward stroke of the piston rod 4, a liquid sample is drawn into the elongated duct 30 through the inlet port 33. During a forward stroke of the piston rod 4, the liquid sample in the elongated duct 30 is pressurized by the piston rod 4 to flow outwardly through the outlet port 32.

In this embodiment, the piston axis, the pump axis, the passage axis, and a cavity axis (to be described below) are in line with each other and are all denoted by the reference letter (P).

The drive shaft 53 is configured to be journaled in the front and rear ends 21, 24 so as to be rotatable about a shaft axis (S) which is parallel to the piston axis (P) and which is opposite to the piston axis (P) in the transverse direction (Y). The shaft axis (S) and the piston axis (P) cooperatively define a vertical plane therebetween.

The main guiding member 50 is disposed under the drive shaft 53, and defines a guideway 51 extending in the longitudinal direction (X) (see FIG. 3). In this embodiment, the main guiding member 50 is mounted on the bottom wall 23.

The carrier block 52 has a top surface 520, a bottom surface 521, a forward surface 524, a rearward surface 525, a cavity 522, and a through bore 526.

The bottom surface 521 is configured to be guided by the guideway 51, and defines a bottom plane orthogonal to the vertical plane, as best shown in FIG. 5. In this embodiment, the bottom plane is parallel to the bottom wall 23. The top surface 520 is opposite to the bottom surface 521 in the transverse direction (Y). The forward surface 524 faces toward the front end 21. The rearward surface 525 is opposite to the forward surface 524 in the longitudinal direction (X). The cavity 522 extends through the forward and rearward surfaces 524, 525 along the cavity axis (P), and includes a smaller-dimension front subcavity 5221, a larger-dimension rear subcavity 5222, and a shoulder abutting surface 5223 therebetween. The through bore 526 is configured to permit the drive shaft 53 to pass through the forward and rearward surfaces 524, 525.

The plug unit 43 is made from a deformable material and has a grip hole 430 which is configured to permit the fixed end 42 of the piston rod 4 to be fitted therein and which extends along the cavity axis (P). The plug unit 43 is configured to be plugged in the smaller-dimension front subcavity 5221 such that the fixed end 42 is retained in the grip hole 430 to thereby permit the piston rod 4 to be moved with the carrier block 52.

In this embodiment, the plug unit 43 includes a plug body 431 disposed in the smaller-dimension front subcavity 5221, and a plug head 432 abutting against the shoulder abutting surface 5223.

The rotary-to-linear motion conversion mechanism 6 is disposed between the drive shaft 53 and the carrier block 52 so as to convert rotation of the drive shaft 53 to linear motion of the carrier block 52 to thereby permit the carrier block 52 to move along the guideway 51 when the drive shaft 53 is driven to rotate.

In this embodiment, the pumping device includes two carrier blocks 52 and two plug units 43. The carrier blocks 52 are displaced from each other in the longitudinal direction (X), and the piston rod 4 extends through a front one of the carrier blocks 52 to a rear one of the carrier blocks 52.

The pumping device may further include a spacer sleeve 7 which is disposed between the carrier blocks 52 and mounted to one of the carrier blocks 52, and which is sleeved on the drive shaft 53.

In this embodiment, the pumping device further includes two auxiliary guiding members 26 which are displaced from each other in the longitudinal direction (X) and which are disposed opposite to the main guiding member 50 in the transverse direction (Y). Each of the auxiliary guiding members 26 is mounted to the top wall 25. Each of the carrier blocks 52 further includes a protruding member 523 which is disposed on the top surface 520 thereof and which is configured to be guided by the auxiliary guiding members 26 to ensure linear motion of the carrier blocks 52.

In this embodiment, the pumping device further includes a driving unit 54 which has an output shaft 541 configured to be coupled to the drive shaft 53 so as to transmit a driving force to rotate the drive shaft 53. Specifically, the driving unit 54 is mounted to an extended frame 22 which is disposed rearwardly of and fixed to the rear end 24 of the frame body 2 so as to permit the output shaft 541 to be coupled to the drive shaft 53.

FIG. 6 shows a pumping device according to a second embodiment of the present invention. In this embodiment, only one carrier block 52 is provided.

With reference to FIG. 4 or 6, in this invention, although the piston axis (P) of the piston rod 4 is offset from the shaft axis (S) of the drive shaft 53 in the transverse direction (Y), the rotary-to-linear motion conversion mechanism 6 is less likely to impart on the carrier block(s) 52 a wavering motion. Therefore, the piston rod 4 can be moved with the carrier block(s) more smoothly and steadily, and is less likely to break. This is because the vertical plane defined between the piston axis (P) and the shaft (S) is orthogonal to the bottom plane defined by the bottom surface (s) 521 of the carrier block(s) 52. In addition, the carrier block(s) 52 is guided by the guideway 51 of the main guiding member 50 that is mounted on the bottom wall 23 of the frame body 2 and the auxiliary guiding members 26.

Furthermore, because the main guiding member 50 and the auxiliary guiding members 26 are disposed oppositely in the transverse direction (Y) for guiding the carrier block(s) 52, the alignment of the piston axis (P) with the passage axis (P) can be further improved.

While the present invention has been described in connection with what is considered the most practical embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

What is claimed is:
 1. A pumping device comprising: a frame body extending in a longitudinal direction and having front and rear ends, and a main chamber defined between said front and rear ends, said front end having a passage extending therethrough and along a passage axis; a pump body defining an elongated duct extending along a pump axis, and disposed forwardly of said front end such that said elongated duct is aligned with said passage with the passage axis in line with the pump axis, said pump body having an outlet port disposed downstream of said elongated duct, and an inlet port which is in fluid communication with said elongated duct, and which is disposed upstream of said outlet port; a piston rod which is disposed in said elongated duct for reciprocating linear motion therein, and which extends along a piston axis toward said outlet port to terminate at a head end, and through said passage into said main chamber to terminate at a fixed end; a drive shaft configured to be journaled in said front and rear ends so as to be rotatable about a shaft axis which is parallel to the piston axis and which is opposite to the piston axis in a transverse direction relative to the longitudinal direction, the shaft axis and the piston axis cooperatively defining a vertical plane therebetween; a main guiding member disposed under said drive shaft, and defining a guideway extending in the longitudinal direction; a carrier block having a bottom surface configured to be guided by said guideway, and defining a bottom plane orthogonal to the vertical plane, a top surface opposite to said bottom surface in the transverse direction, a forward surface facing toward said front end, a rearward surface opposite to said forward surface in the longitudinal direction, a cavity extending through said forward and rearward surfaces along a cavity axis, and including a smaller-dimension front subcavity, a larger-dimension rear subcavity, and a shoulder abutting surface therebetween, and a through bore configured to permit said drive shaft to pass through said forward and rearward surfaces; a plug unit having a grip hole which is configured to permit said fixed end to be fitted therein, said plug unit being configured to be plugged in said smaller-dimension front subcavity such that said fixed end is retained in said grip hole to thereby permit said piston rod to be moved with said carrier block; and a rotary-to-linear motion conversion mechanism disposed between said drive shaft and said carrier block so as to convert rotation of said drive shaft to linear motion of said carrier block to thereby permit said carrier block to move along said guideway when said drive shaft is driven to rotate.
 2. The pumping device according to claim 1, wherein said plug unit includes a plug body disposed in said smaller-dimension front subcavity, and a plug head abutting against said shoulder abutting surface.
 3. The pumping device according to claim 2, wherein said pumping device comprises two of said carrier blocks and two of said plug units, said carrier blocks being displaced from each other in the longitudinal direction, said piston rod extending through a front one of said carrier blocks to a rear one of said carrier blocks.
 4. The pumping device according to claim 3, further comprising a spacer sleeve which is disposed between said carrier blocks and mounted to one of said carrier blocks, and which is sleeved on said drive shaft.
 5. The pumping device according to claim 1, further comprising an auxiliary guiding member disposed opposite to said main guiding member in the transverse direction, said carrier block further including a protruding member disposed on said top surface thereof and configured to be guided by said auxiliary guiding member.
 6. The pumping device according to claim 1, further comprising a driving unit having an output shaft configured to be coupled to said drive shaft so as to transmit a driving force to rotate said drive shaft.
 7. The pumping device according to claim 1, wherein said piston rod is disposed above said drive shaft.
 8. The pumping device according to claim 1, wherein said plug unit is made from a deformable material. 